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of the Great Northern Railway. M. Thouvenot,
on the continent, and Mr. Fairlie, in this country,
combined two tank engines in one, placed, as it
were, back to back, and united as to their
boilers and fire-boxes.

gow, and Edinburgh, in which they were in a
most unsatisfactory state. The municipal autho-
rities of Liverpool had obtained two Acts which
enabled them to obtain an additional supply of
water, and impose certain precautionary condi-
tions on the owners of warehouses, and these In the ordinary system of obtaining adhesion |
Acts had had most satisfactory results. If the by bearing-wheels only, whether of an engine and
appointment of the committee for which he moved tender, or of a double engine, or of two engines
were granted, its investigations might result in coupled together, the weight of the motive
the adoption of similar measures to those which power required to be increased for a given
had worked so well in Liverpool, and through. amount of adhesion, in proportion to the load or
out other parts of the country. The means of as- to the steepness of the gradient. The limit of the
certaining the causes of fires were most scanty, gradient up which such an engine could take a
and the only reports they had to refer to were load might roughly be defined by the co-efficient
those of the London Fire Brigade, formerly made allowed for adhesion. Supposing this to be one-
by Mr. Braidwood, and at present by Mr. Shaw. tenth, then 1 in 10 was (omitting friction) the
The members of the Fire Brigade generally in- gradient on which an engine might move itself,
quired into the causes of fires, but to show the but on which no load could be taken. As on
difficulties in the way of arriving at these causes, the railway over Mont Cenis, the adhesion might
he might mention that in 1864, there were 474 out vary from one-sixth to one-twelfth, and as gra-
of 1,487 fires, the causes of which were not known; dients were required of 1 in 12, it was necessary
and in 1866, there were 589 fires out of 1,338, to adopt some other method than that of trust-
the causes of which were also totally unknown; ing to adhesion by bearing wheels; and having
which was equivalent to 36 per cent. of the a high summit to surmount, it was of great im-
causes of the fires in London last year being un-portance, with reference to cost of working, to
known. He had no doubt the members of the save weight in the engine as well as in the trains.
fire brigade discharged their duties well, and en- By adopting the principle of horizontal wheels
deavoured to find out the causes as conscientiously and a central rail, Mr. Fell, Assoc. Inst. C.E.,
as they could; but he thought it was abso- found the means of doubling the adhesion, at the
lutely necessary there should be some person ap- same time that, by the use of steel, the engine
pointed whose duty it would be to investigate was made lighter than it could otherwise have
the causes of all fires, and receive evidence re- been. This principle was first tested experi-
specting them. It was very probable that if an mentally on the Cromford and High Peak Rail-
investigation were made into fires generally, the way; and subsequently on a line, 1 mile in
result of it would be found most useful, and very length, laid on the road over the Mont Cenis,
probably to assign a large number of them to with an average gradient of 1 in 13, containing
carelessness. Of 9,346 fires which occurred in a curves with radii varying from 4 to 2 chains.
given number of years, 2,500 were said to have The gauge was 3ft. 7. (1:10 metre), and the
been caused by curtains, 1,178 by candles, 932 by middle rail was laid on its side horizontally, at
gas, and 100 by carelessness. It was scarcely ne- an elevation (to its centre) of 7in. above the
cessary to say that curtains would not have ignited bearing rails.
of themselves; and it was plain that a great many
of the fires were caused by carelessness. In
France, Prussia, Poland, Norway, Sweden, and
Denmark, the law required an investigation into
any fire as to the cause of which there was the
slightest suspicion. England was the only country
in which there was no machinery for such inves.
tigation. In conclusion the hon. gentleman pro-
posed his motion for the appointment of a se-
lect commitee.

The engine constructed specially for the Mont
Cenis was partly of steel. Its weight was now
14 tons, and its mean weight, when fully loaded
with fuel and water, 17 tons, of which 2 tons 13
cwt. was for the machinery connected with the
horizontal wheels. There were only two cylin-
ders, each 15in. in diameter, with a length of
stroke of 16in., which worked both the four
coupled horizontal, and the four coupled vertical,
wheels, all 27in. in diameter. The wheel base of
Mr. Kinnaird, in seconding the motion, said the vertical wheels was 6ft. 10in., and that of the
if this country had had the same admirable sys-horizontal wheels was 2ft. 4in. The pressure
tem as prevailed in America and Canada, for the
prevention of fires, the recent lamentable de-
struction at the Crystal Palace would have been
impossible. The motion was then agreed to.

INSTITUTION OF CIVIL ENGINEERS.

upon the horizontal wheels could be regulated
by the engine-driver at pleasure from the foot
plate. This pressure was applied through an
iron shaft, connected by means of right and left-
handed screws with a beam on each side of the
middle rail, and these beams acted upon volute
springs, which pressed the horizontal wheels

a speed of about 12 kilomètres per hour, was stopped in 20 mètres. It was remarked during the later trials, that the engine and train gained speed on the sharpest curves. This effect, so contrary to general practice, was produced partly by the action of the horizontal guide wheels, which kept the engine and the waggons in their proper positions with respect to the rails, and partly to the fact that the gradients on the curves had been slightly eased, while the gradients on the straighter portions had been made proportionally steeper, with the intention of as nearly as possible balancing the resistances.

Another system for working steep inclinesthat of Signor Agudio-had found support in Italy. In it two stationary engines were em. ployed, one at the summit and the other at the bottom of an inclined plane, which acted upon the same double endless rope, kept stretched by a tension waggon hanging upon it at each extremity. This rope ran between the rails, and over two sets of wheels worked by the stationary engines, from which it received its movement by friction. It did not act directly upon the train, but was connected with an engine, called the "locomoteur funiculaire," supported on a bogie frame at each end, and carrying a system of drums and wheels, by the action of which the required motive power was obtai ed indirectly by the moving rope. Experiments tried with this system on the Dasino incline between Turin and Genoa in August, 1863, appeared to have given great satisfaction to the Commissioners of the Royal Institute of Lombardy. But the author was inclined to think that neither this system, nor any other yet developed, could com. pete with the central-rail system for general traffic on gradients up to 1 in 10 or 1 in 12.

For mountain passes the author believed the middle-rail system possessed great advantages. Besides being of service in the ascent, it afforded the means of employing pressure brakes, acting with any amount of force, to any number of vehicles, and thus rendered the descent safe, and supplied a remedy against bad consequences from a fracture of the couplings. It also prevented the engines, or any vehicles of the train that were supplied with guidewheels, from leav ing the line, from a defect in the permanent way or rolling stock. A country which required very steep gradients demanded also, in most cases, very sharp curves; and the central rail contributed to safety as much in respect to the latter as to the former. On the Mont Cenis Experimental Railway, the bearing-wheels of the engine left the rails on two occasions, and on both they were brou ht back to the rails by the guiding power of the central rail. As, however, in the course of about three months, the line was expected to be opened from Susa to Lansle

AT the Institution of during or Modane, and in from

gineers held on March 5, John Fow. ler, Esq., president, in the chair, the paper read was "On the Working of Steep Gradients and Sharp Curves on Railways," by Captain H. W. Tyler, Assoc. Inst. C.E. It was remarked that the comparative terms, steep and sharp, had acquired at the present day a signification very different from what they conveyed to en gineers a few years since. The locomotive engine had been gradually trained and adapted to gradients of 1 in 100, 1 in 50, 1 in 25, and 1 in 12,

combined with curves of from 30 chains down to

15, 10, 5, and even 2 chains radius; and during all this progress, the result of so much labour and ingenuity, the system of bite, or adhesion, by plain surfaces, had steadily triumphed as a means of converting steam power into tractive force. The co-efficient of adhesion was always in the first instance under-estimated; and the central rail system, first patented by Mr. Vignoles, M. Inst. C.E., and Mr. Ericsson, on Sep. tember 7, 1830, was intended to provide extra adhesion on what were now considered moderate gradients, in place, apparently, of the well. known rack-rail of Blenkinsop.

the experiments was from 2 tons to 3 tons on each horizontal wheel, or 10 tons altogether; but the pressure actually provided for, and which might, when necessary, be employed, was 6 tons upou each, or 24 tons upon the four horizontal wheels. The vertical wheels were worked in. directly by piston rods from the front, and the horizontal wheels directly by piston rods from the back of the cylinders. The results of the dif ferent experiments on the Mont Cenis Experimental Railway were given in several tables, which showed that considerably more could be accomplished than had been proposed in the programme handed to the French and Italian Governments. During the official trials, in the month of July, 1865, before the French, Italian, and Russian Government Commissioners and others, with a load of 24 tons, exclusive of the engine, the distance run in fifteen trips was 51040 kilomètres (31 miles, nearly) at an aver age speed in ascending of 10-704 kilomè res (6 65 miles) per hour; while with a load of 16 tons, the distance run in eight trips was 29 12 kilomètres (1809 miles), at a speed of 15'6 kilomètres (10 miles nearly) per hour. During these In conveying heavy loads up gradients much twenty-three trips, the pressure of the steam inless steep than several which had been worked, creased 500lb., or 21lb. on the average for each for a greater or less number of years, with en- run. In the month of November, 1865, when gines of ordinary construction, a want of extra some other trials were made, a maximum speed adhesion had been seriously felt, and various ex- was attained of 12 kilomètres (7:46 miles) per pedients had been resorted to for obtaining it. hour, with a load of 24 tons, and of 15 kilomètres M. Flachat proposed, in constructing railways (11.2 miles) per hour, with a load of 16 tons. over the Alps, to utilise the adhesion not orly of As evidence of the power of the brakes, it was all the wheels of the engine and tender, but also, stated that when the ordinary and the central by the use of additional cylinders, &c., to them, rail brakes were combined, with a gross load of of all the vehicles composing a train. Mr. Stur- 41 tons, descending a gradient of 1 in 12, at a rock had added cylinders and the necessary ap-speed of about 6 kilomètres per hour, the train paratus to the tenders, and employed them for was stopped within 20 mètres; while, under some time as assistant engines on certain parts similar circumstances, a gross load of 33 tons, a

from the present time throughout its whole length of 48 miles between St. Michel de Maurieune and Susa, there would then be an opportu nity of becoming better acquainted with this pian.

THE

This in.

NEW TELEGRAPH INSTRUMENT. HERE is now on trial at the chief office of the London District Telegraph Company, in Cannon-street, a telegraph instrument which, in point of detail and result, appears to be the nearest approach to simplicity and perfection hitherto available for public or private use. It is a printing instrument, producing letters printed in ordinary type by means of pressing small keys bearing the respective letters. It is worked says the Star, by a combination of clock work and electricity, and has now been in use for some weeks without a single derangement. Other somewhat similar results have been arrived at by other instruments, but with the exception of that invented by Professor Hughes, none have been brought into successful use. strument has, however, many advantages over that of Professor Hughes. It does not exceed 15 square inches in size. It is extremely simple in all its arrangements, is portable, and costs less than a third of that invented by Professor Hughes These many advantages render it particularly suitable for private telegraphs, as any one can work it. A printed record is kept of the message, and should no one be in attendance to receive a message when transmitted, the printed slip will remain for attention as soon as anyone is present to attend to it. Should the proposed annexation of the telegraph to the General Post Office be carried out, this will be a most useful instrument for use at all the minor post office and telegraph stations.

MODE

SOCIETY OF ENGINEERS.

(Concluded from p. 151.)

ODE of Screwing. In order to accomplish the screwing operation in the cheapest and most expeditious manner, it was considered better to dispense with a scaffolding supported by timber piles, as with the then existing depth of water, powerful current, and frequent sudden floods, there was danger of the whole platform being swept away, as happened during the building of the stone railway bridge about a mile lower down the stream. Instead of an ordinary scaffolding, therefore, two of the largest river barges were hired, which served as pontoons; these were firmly braced together by cross timbers fastened over the decks, leaving sufficient space between the barges for sinking the pile and screw. The whole framework was then well planked over for the men working at the capstan to walk on. A stout rope extended across the river with a travelling pulley, from which another rope was attached to the barges. From the stem and stern of the latter four guy ropes stretched up and down stream to capstans fixed to both hores, so that the stage was under perfect command. This arrangement had the advantage that the whole apparatus could be moved, with little loss of time, to any point where a pile was to be pitched, and, in fact, the stage was floated from one pier to the other, across the river, in a couple of hours; further, during the frequent changes in the water level, the working platform always remained at the same height above the water. On the other hand, a drawback accompanied this arrangement, which was the great difficulty of keeping the piles perpendicular whenever the screw met with an obstacle which forced it out of its centre, as even the strongest ropes would then stretch, and it required the constant attention of the men at the guy ropes to slacken or tighten them.

was cut into four equal lengths, 3ft. 9in., and
these were firmly bound with hoops notched into
the edges.

This new ram weighed 8 cwt., and the wooden
ones from 14 cwt. to 2 cwt. The fall varied from
3ft. to 10ft., according to the nature of the ground.
During this process of driving the screws, it was
found that, as is the case in all pile-driving, there
wasa considerable rebound after each blow; and

SECOND SCREW-FIG. 2.

in order to counteract that, and take full advan-
tage of the force of the blow, it was found neces-
sary to give a quick and sudden tura to the screw
the very instant the monkey fell, even a quarter
of a turn at the capstan sufficed, and thus no
ground was lost. Four smaller capstans were also
added, placed round the central one, and, on an
average, forty men were employed. In conse-
quence of all these delays, amongst which was the
breaking of the capstan boss, nearly four months
elapsed before the fourth pile was driven home,
although it required less than six weeks to
drive the second pair of piles, which were no less
than 16ft. in the ground. Another and not the
least obstacle to progress was the great number of
holidays which had to be strictly observed,
occurring in the middle of the week, which not
only caused delay through loss of time, but also
through the demoralising effect on the workmen,
as on the day following the holiday a much less
amount of work could be got out of them. In other
respects, the writer must do the Italian workmen
justice in asserting that they are intelligent, and
that the better class of them, when properly
encouraged, work willingly.

The screwing operations were commenced on May 22, 1863. The first 24ft. were penetrated by the screw, with the aid of twenty-five men, in about two days, but below that point it was found impossible to drive it, as it rose over the obstruction instead of going through it, and after a whole day's grinding the progress made did not amount to half an inch. The pile was then raised, and it was found that the circumference of the screw, although armed with a serrated edge, according to Mr. Wells's recent patent, was worn away to a depth of 5in. from the circumference. This naturally gave rise to the surmise that one of the threatened boulders had been encountered, but as the same features presented themselves in every instance, it became evident that the obstacle was not an accidental one, and it was afterwards ascertained beyond a doubt that the river bed was indeed covered with a stratum of compact though easily penetrable gravel to a uniform depth of about 3ft., but that underneath this was extending a bed of extremely hard natural concrete, of unknown thickness, but of tolerably homogeneous Modo of Erecting Bridge. The girders for the texture. That this bed was of limited extent, first span were erected on shore, and placed on however, was proved by the fact that during the lorries made for the purpose; the outside end of building of the already mentioned railway bridge, the girder was then suspended to the tackle of the a solid foundation was only with the greatest floating stage, and brought forward until it rested difficulty obtained, and recourse was to be had to on the base plate over the pile. After the first extensive piling. It was evident that the present two girders were thus fixed, the cross girders were screw was not of a shape fitted to penetrate this laid at once, and a temporary flooring made with ground, and the writer therefore applied again to planking on which to erect the second pair of Mr. Wells for his advice, who offered to send out girders, which were towed into their position in at once new screws of 2ft. diameter, as proposed the same manner, and so on with the last girders. by him at the first, and which screws no doubt In this manner, any extra expense of erecting a would have fully answered their purpose; but the scaffolding in the river was avoided, the same delay occasioned by the transport opposed an barges serving also for erecting the bridge. In obstacle to this remedy, and the writer had, there- addition to Mr. Wells, to whom the writer was fore, new screws cast in Venice, of 2ft. 9in. diame. indebted for his valuable assistance and advice, ter, and the same in depth, the thread going twice he has further to acknowledge the services of Mr. round, with a pitch of 12in. Mr. Wells thought William Parsey, C.E., who assisted him in the that such a steep pitch would require more power design and calculation of the girders, and also to drive the screw than was available, and fixed superintended their execution in this country. upon 8in. as the maximum, but his advice came This part of the work was most creditably perunfortunately too late. It was not long before formed by the firm of Messrs. Porter, of the TiviMr. Wells's predictions were verified; and, in orderdale Ironworks, in Staffordshire. It may be to obtain the necessary driving power, recourse observed, however, that neither the writer nor was then had to blows, at first by sledge hammers, Mr. Parsey can be answerable for the design of and afterwards by a pile-driving engine, the the details of these girders, of which they did not monkey acting on the top of the pile; but as the approve, it being an antiquated combination of rams used in that country consisted simply of wrought and cast iron; but the writer was obliged blocks of oak bound with hoops, and the blows to conform to a design previously sanctioned by upon the hard surface of the pile would have the corporation. It was, moreover, necessary to injured the timber, a wrought-iron plate was employ a greater amount of cast iron in the conscrewed with wood screws on the bottom of the struction than was desirable, on account of the ram. Notwithstanding this precaution, the hoops enormously heavy duties on foreign wrought iron. flew off, injuring the men below, and the monkey The cost of the two piers, including first cost of was soon smashed to pieces. The only substitute the iron in England, freight to Verona, import then available consisted in a wrought-iron square duty, and erection complete, was £1,400, while bar 4in. by 4in., of excellent German iron. This the cost of two stone piers, estimated by Italian

architects for a bridge of three iron arches amounted to £2,600.

Conclusions from the foregoing.-1st. Cause of Floods. While writing out the above account, a few considerations suggested themselves to the mind of the writer, which he wishes to submit to this meeting, trusting to be favoured and enlightened by the remarks of more experienced members. The first subject of importance, upon which there will hardly be a difference of opinion, is that of the increasing violence of inundations and their causes, consisting, as is now ascertained beyond a doubt, in the indiscriminate cutting down of the trees on the mountain slopes. Although it may justly be objected that this is a subject totally irrelevant as regards this country, it will not be denied that it deserves a passing mention respecting the East Indian empire, a country of yearly increasing importance to the English engineer. There the circumstances are analogous to those described, and as Anglo-Indian engineers had to go into Italy to study the best system of irrigation, they might at the same time have taken warning how not to waste the resources of nature. The writer noticed, therefore, with pleasure, in one of the latest numbers of Engineering, that the present Home Secretary for India, with a wise foresight, has taken the necessary steps in time in organising a staff of forest engineers, through whose supervision alone the wholesale destruction of timber, as well as the frequently recurring inundations, can be prevented.

2nd. The Use of Screws.-The second subject for consideration that occurred to the writer is the choice of the most fitting substructure for a bridge. This, of course, is entirely dependent upon the locality, the abundance or scarcity of building material and of labour, and the nature of the foundations. From the writer's limited expe. rience, he is inclined to think that screws, with either wrought or cast-iron piles, may be employed in any ground short of the hardest rock (although some of Mr. Wells's screws have penetrated pretty hard limestone), and that they can be oyed with greater economy both of time and money, in most cases, than piers of brick or masonry, whether they be enclosed in cast-iron cylinders or not, and especially in waters where the current is rapid and the river-bed uneven, as one screw may be sunk to a lesser or greater depth than another in its immediate vicinity without affecting the stability of the structure, and the screwing may take place at all seasons independently of the water level. In the present instance the work was com menced at a time when no native engineer would have ventured to lay a foundation in such a river as the Adige previous to the month of November, whereby six months would have been lost, which, to a speculator anxious for a quick return for his outlay, cannot be indifferent. The writer fully admits that for monumental structures, such as bridges in a large town, that are expected to be slender, iron columns are inapplicable; but these are exceptional cases.

3rd. Comparisons between Wrought and Cast Iron Piles. The third consideration which the here-mentioned operations suggested to the writer is, that wrought-iron solid piles, in one length wherever practicable, are preferable to hollow castiron pipes, although the greater first cost of the former might deter an engineer from employing them. The choice between the two materials will again be dictated by local circumstances, but in the case of rivers subject to heavy floods, with the constant danger of heavy masses being hurled against the piers, one would think the choice could not long remain doubtful, as any saving in the first cost could never compensate for the loss of the whole structure. Another advantage possessed by iron and, above all, wrought-iron piles, lies in the small surface they oppose to the current, which entirely obviates the danger arising from the scour and consequent undermining of the piers. In corroboration of this, may be mentioned the fact, that during the heavy floods of last autumn in the mountains of France and Italy, massive stone piers were swept away, while apparently fragile timber structures supported by a few wooden piles remained unscathed. The Italian engineers in those parts are in the habit of protecting their stone piers of bridges by heaping up a quantity of loose stones around them, so as to break the force of the current, and it was with some difficulty they were persuaded to omit this practice in this instance; but when they saw that in a flood which occurred in September, 1863, the iron piles remained unmoved, they were perfectly satisfied. Another circumstance in favour of the piles adopted in the Adige is the testimony of the

bargemen navigating that river, that they pre-equipments. The hospital yard has a park of many boilers in so long a time, and even those ferred the passage under that bridge to any other, field artillery numbering over 300 pieces, neatly few reported as dangerous, clearly show the as there is no contraction of the waterway, and arranged on skids. The value of these guns and system of periodical inspection is of great benefit. consequently the velocity of the current was not stores must be nearly one million dollars. They During the past year there have been made so great as under bridges with massive piers, were sent there from the South and South-west 11,523 inspections of boilers, and of these 1,380 where, as is well known, the utmost skill in after the war. The old prison buildings are have been inside, and 1.367 in the flues. During steering is often required to avoid disasters, taken down as fast as the lumber is needed. the year, 1,168 reports have been sent to owners, From this lumber a large temporary machine-pointing out matters needing attention. shop, carpenter and blacksmith shop has been constructed. An engine of 80-horse power, and a good assortment of first-class machinery are now running and in constant use. The avenues are opened and some of them graded and partly macadamised.

THER

ROCK ISLAND ARSENAL. HE Chief of Ordnance, in America, in his annual report, urged the importance of building additional workshops, armouries, &c., at Rock Island, Ill. The following is an account of the Arsenal at that point, as it is and as it is proposed to make it, and which we take from the American Army and Navy Journal :-Rock Island contains about 1,000 acres; is situated in the Mississippi River, and lies in the state of Illinois; is about two miles and a half long, average breadth three-eighths of a mile. It is separated from the Illinois shore by a slough of healthy running water, the main channel of the Mississippi being on the Lowa side. Opposite the lower end of the island, on the Illinois side, is the City of Rock Island, a place of about $,000 inhabitants. On the Iowa side, directly opposite Rock Island City, lies the beautiful City of Davenport, picturesquely built on the side of a river bluff and along its foot. Delightful landscape views can be enjoyed from very many private residences in the town. It has a population of over 15,000, and will, in time, become quite a large Western city. At the head of the island, on the Illinois shore, we find a lively manufacturing town of 3,000 inhabitants, called Maline. The United States Government intends building an arsenal and armoury on the island, to replace the one destroyed at Harper's Ferry. Brevet BrigadierGeneral T. J. Rodman, Major of Ordnance, is in command, and has submitted a plan to the War Department, for the location and construction of the extensive shops, storehouses, &c., which it is

proposed the sports thes, Clan has been

approved, and operations have been commenced in accordance with it. If Congress makes the appropriations aaked for this session, some of the large buildings will be commenced next spring. One large stone storehouse, at the lower end of the island, is now nearly completed. It faces Davenport, is 180ft. by 60ft., has a basement, three main stories and an attic. It was located and commenced by Major (now Brevet BrigadierGeneral) C. P. Kingsbury, Ordnance Department, and, under General Rodman's plan, is to be used as a receiving and issuing storehouse. There will be a landing on the river bank nearnit.

At avenue 150ft. wide will run the whole length of the island, nearly east and west. The main buildings will be erected near the centre of the island, on both sides of the main avenue, on the highest ground, giving good drainage and dry basements. The plan contemplates the erection of ten large stone buildings, five on each side of the avenue, to be used as shops for the manufacture of small-arms, iron and wood guncarriages, field, siege, and sea-coast. Each building will have a basement and two stories, will be built on three sides of a rectangle, having a frontage on the main avenue of 225ft., and running back 300ft., the wings on each of the three sides to be 60ft. wide. In rear of each of

On the south side of the island, along the slough, the magazines, laboratories, and gasworks will be located. There is an excellent water-power at the upper end of the island, on both sides. It is proposed to make use of the power in the slough to compress air, which will be conveyed in iron pipes to the shops. All the shops will be provided with steam engines; the compressed air will be worked through the steam cylinders, and the steam engines need only be used when the water-power fails, which will be at least three months in each year. The power on the Mississippi side is to be used for raising water, which will be carried in pipes to the shops and quarters, and to the fountains and reservoirs. The Chicago, Rock Island, and Pacific Railroad crosses the island, cutting it in bad shape, and efforts are being made to have it removed to the lower end of the island, and have the new bridge made of iron, with double track and waggon road, to be 50ft. above high water, so that steamers with telescopic chimneys can pass under. The present draw-bridge is a serious obstruction to navigation. The waggonroad bridge to Davenport is greatly needed by the government, as the only communication between the island and Davenport (for waggons) is by Rock Island and a ferry. A railroad will connect the shops and storehouses with each other, with the receiving and issuing storehouses,

and the landing, and the Chicago, Rock Island;

and Pacific Railroad. The Chief of Ordnance recommends an appropriation of five millions of dollars for immediate use in building the arsenal. It is a measure of sound policy and economy, unless the old proverb "In time of peace prepare for war," won't apply in modern times. The position has many advantages. Its means of communication by rail and water are excellent, and its interior location makes it safe from foreign enemies. Being surrounded by water it is easily protected, requires no heavy brick or stone walls about it. Long ranges can be obtained for experimental firing, and there is a good place for a powder-mill; plenty of room for furnaces and foundry, with the Iron Mountain of Missouri in easy reach to furnish ore, and the inexhaustible coal-fields of Illinois for coke; lead mines all about it and Wisconsin copper mines only a short distance away. Where will the government find a better place for the great arsenal of the country? It can and should be made the finest and best arsenal in the world. Woolwich Arsenal, England, and the Vienna Arsenal are now accounted the greatest; but the first is a mere batch of machine shops, without order or system, and the second a relic of times gone by-entirely behind the age.

By far the most frequent cause of injury to boilers has been found to be corrosion, especially externally, where the plates have come in contact with the brickwork; needless danger is also often caused by the over-weighting of the safety valves. Very great mischief is also allowed to be done by want of timely repair, or by the straining of repair hastily

executed.

Records have been obtained of 70 boiler explosions, during the year 1866, in Great Britain, causing the death of 85, and the injury of 160 other persons. The class of boiler which has most frequently exploded, and has caused the most loss of life, is the Cornish or two-flued boiler, internally fired, and the records show that this otherwise safe and economical boiler reof construction, especially in the strengthening quires attention to certain well-established details of tubes of large diameter with rings; and also that the shell is as liable to corrode, and that corrosion is as dangerous to this as to any other

class of boiler. The causes which have led to

the greatest number of explosions have been faulty construction and corrosion. In nearly every case the cause was readily to be discovered, and the evil could have been avoided, or remedied, had the boilers been subjected to proper periodical inspection. Various statistics, and other matters of general interest, are given in an appendix to Mr. Marten's report, together with brief abstracts from the records of explosions, which are fully illustrated by engravings which present the whole matter at a glance.

A

SCIENCE AND CHIGNONS.
Ta meeting of the

Society of Lund members of the Harvian

7th inst, the scientific points involved in the chignon question were commented upon by Dr. Tilbury Fox in a paper which had reference to the influence of parasites in the production of diseased conditions of the skin. It has been asserted, first, that false hair contains the germs of pediculi, which are developed by the warmth supplied by the human head; secondly, that bodies called gregarinæ exist in false hair, and may become pediculi. The first statement is wholly incorrect, but the so-called nits are nothing but empty shells, whence the young pediculi have escaped. The female pediculus lays her ova at the part of the hair close to the scalp; in six days the young are hatched, the empty shell is carried forward by the growing hair, and as this is cut from the head at the distance of from one to two inches, no true ova are brought away with it. The inference is clear that no false hair ever contains the materials from which pediculi develope, and where these are present their existence must be accounted for by uncleanliness. The second statement is equally untrue; gregarines are only found in Russian hair, which does not enter the English market; they have vegetable affinities, and never give rise to any form of insect. In his large experience of diseased states Dr. Fox stated he had never seen them once on the hair. Lastly, he

the two rows of buildings above described, and MIDLAND BOILER ASSURANCE COM. described a real source of danger as yet unseparated from them by two wide avenues parallel to main avenue, will be five more build

avenues.

PANY.

ings (ten in all), 225ft. by 60ft., same height and MR R. E. B. MARTEN, the engineer to the above
company, has just made his half-yearly re-
material as the other buildings. These will be
used for offices, barracks, store-houses, &c. Two port, in which he states that up to December 31,
avenues, 150ft. broad, cross the island from 1866, there were 890 boilers under inspection,
north to south, at right angles with the main and 1,300 under assurance, making a total of 2,190
boilers under the care of the company. This
avenue, and all the buildings will be included number has since been considerably increased.
between them. They are called North and South There has been no explosion of any boiler under
On the Mississippi, between it and the care of the company during the past half
South avenue, and north of the buildings, there year, nor indeed during the whole of the past
will be a large and beautiful park. On the same pear, excepting one of a very trivial character.
ground now stand many of the barracks used by During the five years the company has been in
the rebel prisoners during the war. At one operation, there has been only one serious claim
time the prison had 10,000 rebels, and 4,000 upon the guarantee fund for an assured boiler,
Union soldiers to guard them-14,000 men! and even that would have been prevented if the
Davenport's rival in point of numbers. 2,000 warning given of the danger had been attended
rebels and 200 Union soldiers died during their to. Two other serious casualties have happened
stay, and are buried on the island. The prison to boilers under inspection in the five years, one
hospital consisted of fourteen wooden buildings, before opportunity of internal examination had
125ft. by 20ft. They are now filled with small- been given, and the other after the danger had
arm ammunition, infantry, cavalry, and artillery | been reported. So few explosions among so

noticed by any observer. On some of the light brown or reddish false hair of German origin, he had found a species of mildew fungus, which unquestionably would, if implanted upon the surface of weak persons, give rise to ringworm, and he produced microscopic evidence and instanced cases in which he had apparently seen mischief result in this way. Cleanliness is a great preventive of evil, and such hair should be subjected to proper processes to ensure protection against the production of disease. While the great majority of the statements that have been made recently about chignons are wholly untrue and absurd, there is no doubting the fact that without proper precaution the use of false hair may give rise to certain uncomfortable conditions of the part next which it is worn, but that even this source of evil may be remedied.

In the year 1866, 48,441 cwt. of books-more than 5,000,000lb.-were exported from the United Kingdom." Their value, as registered at the Custom. house, was £602,177, a little over 26d. per lb.

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THE

IMPROVEMENTS IN THE CONSTRUC. TION OF PNEUMATIC RAILWAYS. THE Waterloo and Whitehall Railway, now in course of construction under or rather through the Thames, is to be worked on the pneumatic principle, as our readers are doubtless aware. The development of this principle is due to Mr. T. W. Rammell, of 3, Westminsterchambers, Westminster, who is the engineer of the line in question, and who has practically applied his principle in working the pneumatic despatch tubes beneath the streets of London. Since the opening of these tubes Mr. Rammell has made several improvements in the system which he has recently patented. These, however, apply chiefly to passenger lines, and will be carried out in the Whitehall railway, which, we are glad to learn, progresses satisfactorily in a constructive point of view, and there is every probability that the line will be opened for traffic during the present year. One of Mr. Ram. mell's improvemerts consists in an improved arrangement of the terminal parts of pneumatic railways. Formerly, double sets of terminal doors were applied to single lines of railway, the embranchment of the ways being effected within the limits of the tubular way. Mr. Rammel now improves the arrangement of these parts by setting the terminal doors backwards from the station towards the tubular way sufficiently far (say, from 100ft. to 120ft.) to allow of the embranchment of the ways being made between the tubular way and the platform of the station, enlarging the intervening covered way (if any) for the purpose. In this manner he is enabled to work single lines of pneumatic railway running into the double ways required at stations with single sets of terminal doors. Another improvement consists in an arrangement for giving motion to the trains at stations, where the train being wholly outside the tubular way the pneumatic pressure cannot be brought to bear upon it. To obviate this inconvenience the ways at all

stations are laid at an inclination downwards from the station towards and into the tubular way, and at a gradient (say about 1 in 60) sufficiently steep to give a proper velocity to the train on the breaks being released. At terminal stations the ways are thus made to fall entirely towards the tubular way, and arriving trains are received and brought to rest upon a rising gradient. At intermediate stations the ways fall from a summit near the middle towards the tubular way on either hand, and arriving trains are made to pass over this summit by the momentum they have acquired, and are brought to rest upon a descending gradient, where they are in a position to be again put in motion by gravitation, and to run into the next section of the tubular way on the breaks being relieved. The necessity for using any additional appliances to put the train into motion at stations, or for running the head or leading part of an arriving train into the entrance of the forward section of tubular way with that object is thus avoided.

We next have some improvements in the arrangement and construction of Mr. Rammell's pneumatic ejector, in order the better to adapt it to the working of passenger railways, and for other purposes where large quantities of air have to be dealt with, and the machine must conse. quently be of large size. These improvements are shown in our engravings, where fig. 1 represents a plan, fig. 2 a transverse section, and fig. 3 a longitudinal section of an ejector designed for the purposes in view. To avoid the inconvenience of too great distance between the points of support, the bearings of the shaft are placed intermediately between the exhaust passages H H1 on either side, and the middle or pressure chamber I I I, they are fixed on girders carried across the indraught openings in the side walls of the chamber, and so formed as to impede as little as may be the flow of air into the machine. The connection between the exhaust passages and the entrances of the ejector is completed by means of mouth pieces attached to the walls of

the pressure chamber around the openings described. This arrangement is shown at BBB in all the figures. In constructing these machines of large diameter, in order to obtain the greater accuracy of form and lateral stiffness in. the outer parts, Mr. Rammell uses metallic rings of sufficient substance. These stiffening rings are affixed externally to the principal rings KK, which radiate from the central parts of the machine, and are set up from their base into true position, and by the lateral assistance they afford and the stiffness of the rings between them Mr. Rammell is enabled to bring the intermediate and outer ribs L L, which have no sufficient base from which they may be set up, also into true shape. The arrangement of these rings is shown at C C C, figs. 1 and 2.

Another improvement refers to the arrangements of the valves and air passages of these machines, which are of considerable size. As the most convenient arrangement the supply and escape valves are placed in the upper part of the machine, where they open freely into the outer air, and their indraught discharge currents having a vertical direction occasion no inconvenience. The arrangement is shown in figs. 2 and 3, where D D1 D represent the supply valves, and E E the escape valves. The exhaust and pressure valves are placed in a vertical position below ground at one end, or cn one side of the machine. This arrangement is shown in figs. 1, 2, and 3, F F being the exhaust valves, and G G1 the pressure valves. These valves are shown in duplicate, being applied to an ejector intended for the working of two sections of tubular way. These valves open into a common chamber communicating with the connecting air way of the tubular way, through which s ngle connecting air way both the pneumatic pressure and exhaust can be applied to the train by an independent valve, which is termed the main valve, and which is placed near the junction of the air way with the tubular way. In all cases balanced valves set n iron frames are used, and

by means of gearing the exhaust, pressure, escape, and supply valves are connected together in such manner that they may be worked together or separately from a common and convenient point, and either by hand on the spot, or by intermediate appliances from any distance.

Another part of this invention consists in connecting the various valves at whatever distance the pneumatic machinery may be situate from the station, and also the terminal doors with a room, which is called the signal room, from which, with proper apparatus and appliances, and the aid of pressure gauges and telegraphic signals, they may all be worked with a single ope. rator. For the greater certainty and safety of working this room is placed either in the station or near the termination of the tubular way within view of the arriving and departing trains.

We now come to the piston carriages. In the working of pneumatic railways resistance is now experienced in a train entering the tubular way from the inertia, or from the opposing momentum, as the case may be, of the mass of the contained air. In order to remedy this incon. venience, and insure the easy entry of the train into and its free movement within the tube, and also to enable the driver to regulate the application of the pneumatic pressure to the train, and to liberate from pressure at the proper moment the terminal doors, so that they are free to open for the exit of the train, Mr. Rammell makes the sail plate of the piston carriage of a train partty of fixed and partly of movable parts, which latter by suitable apparatus under the control of the driver may be contracted or folded up, or ex. tended or expanded at pleasure, so as to fill up more or less completely, as desired, the transverse area of the tubular way. About one. fourth of the entire area of the sail plate is thus made movable, that proportion of opening being sufficient to allow of the free movement of the train through the air in the tubular way. The mov. able portion of the sail plate is hung in two equal divisions, one on either side of the piston car. riage. This arrangement is shown in fig. 4, in which N N represents the movable parts of the sail plate, and the apparatus for folding up and extending these movable parts is shown at 0 0.

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Finally, Mr. Rammell has improved upon the permanent way of pneumatic railways, which it is desirable should be compact in size, securely fixed, and smooth and easy in use, and also capable of ready adjustment and renewal. The way is laid in iron chairs built into the brickwork or masonry of the tube, and sufficiently large to contain the rail with packing pieces of wood beneath it and on both sides. The chair is wedge-shaped, and has a table to receive the lower packing piece upon which the rail rests, and by the greater or less thickness of which its level is determined. This piece is made somewhat elastic, either by hollowing out the slab of elm or other hard wood composing it, or by combining with the piece a layer of cork, caoutchouc, or other elastic material, or by the use of a steel spring. The sides of the chairs and rails drawing of the same part. One of the prominent are to be so formed that wedges or packing pieces of greater or less thickness may be inserted on either side, and by these the rail is not only held firmly in position, but is set laterally to true

gauge.

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In the upward stroke, the tongue ƒ of the piece features of the machine consists in the false bot- D (see figs. 2 and 3) catches the spring with the tom or heading alluded to, and which is designed handle g, and connects it with one of the slots in for the purpose of obviating the serious results the sector h. This latter piece is fixed on the attending the rupture of the piston rod when the axis i, which is attached to the lever J, which motion of the piston is not arrested in due time. sets the slide in motion by the rod M (see fig. 1). The desired object is fulfilled as follows:-During The whole action may be thus briefly summed the whole time the piston is in motion steam is up. The hammer communicates motion to the NEW STEAM HAMMER. caused to enter through the aperture A bar C, which causes the piece D to rotate on its VINCE the increase in the size of the masses (see fig. 1), into the part above the flat disc B, axis and to become connected through the spring of steel and iron now subjected to the action which has its lower surface of a smaller area thang with h, which is attached to the lever moving of the tilting and forging hammer, it has become the upper. This inequality of the two areas the slide rod M. The piece h is furnished with necessary to increase the power and efficiency of causes the pressure of the steam entering about as many grooves as there are different descripthe agent which reduces them to the required the disc B to be greater than that acting upon tions of stroke required in the machine. The shape and consistency. Nearly every iron im- its lower surface, and consequently the disc will rod K, by means of the spring L and lever R, plement manufacturer has produced a steam not move in the slightest degree while the ordi- serves to reverse the position of the slide so soon hammer with particular modifications and altera-nary action of the machine is in progress. as the tongue ƒ has disengaged itself from the tions in accordance with his own ideas on the Directly the piston becomes detached from its spring g, and the hammer has reached the end subject, and recently one more has been added end, it strikes against the false bottom B, which of its stroke. The up stroke then recommences, to the list and patented by M. Rivollier. In the rises and compresses the steam between it and and the action of the machine proceeds as we annexed cuts this machine, which is double the cover of the cylinder. As the steam in this have already described. When the lever N (see acting, is represented, and the inventor claims space has no means of exit it acts like a cushion, figs. 1 and 2) bears upon the lugn the slide occumany especial advantages for it. To prevent and by its own elastic force, speedily brings the pies an intermediate position and the hammer is the fracture of the shank or rod carrying the head, disc B back to its normal position, as represented brought to a state of rest. By means of the lever causing the piston to leave the cylinder, a false in fig. 1. R and this arrangement the slide can also be bottom is applied to the upper end. There is worked by hand. If desired, the piece D with also an especial arrangement of the slide valves, the other parts in connection with it can be placed resulting in great simplicity of action and the directly on the head of the hammer and the inuse of equilibriated discs. Fig. 1 is a face elevatervention of the bar C dispensed with. In large tion of the hammer, one-half of which is in secworkshops, similar to those of Krupp at Essen, tion; fig. 2 is a portion of the side elevation, steam hammers of enormous power are employed showing the mechanism connected with the to produce the necessary forgings for armourmovement of the valves; and fig. 3 is a detailed plates and cannons, and there is no doubt but

The slide valve is set in motion by a mechanical combination, which certainly is not so simple as many others that are in present use. The bar C (see figs. 1 and 3) is attached to thg head of the hammer at 2, and slides alone the socket of the conical or wedge-shaped piece D during the reciprocating motion of the ham mer, imparting to D a rotary motion on its axis.

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